. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ULTRAVIOLET RADIATION AND PHENOCOPIES RESULTS Larvae show a gradual increase in sensitivity to ultraviolet radiation with age from 50 to 100 hours after hatching to a maximum at one hour after pupation, then a sharp decrease in sensitivity with pupal age. The sensitivity of flies to ultra- violet at an intensity of 44 ergs per per second for different durations of exposure, as measured by the percentages killed, is given in Figure 1. '440 i "660 = 1320 • =2640 ERGS/MM2 -=13,200 ERGS/MM
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ULTRAVIOLET RADIATION AND PHENOCOPIES RESULTS Larvae show a gradual increase in sensitivity to ultraviolet radiation with age from 50 to 100 hours after hatching to a maximum at one hour after pupation, then a sharp decrease in sensitivity with pupal age. The sensitivity of flies to ultra- violet at an intensity of 44 ergs per per second for different durations of exposure, as measured by the percentages killed, is given in Figure 1. '440 i "660 = 1320 • =2640 ERGS/MM2 -=13,200 - + •••=26,400 FIGURE 1. 40 50 60 70 80 90 100 I 1-3 3-7 7-12 12-24 HOURS AFTER HATCHING HOURS AFTER PUPATION AGE AT IRRADIATION Percentage of flies killed by different total dosages of irradiation at different ages given at 44 The percentage of flies showing phenocopies also varies with the age of the larva or pupa irradiated (Fig. 2). There seem to be two periods during the larval stage of greater phenocopy production for a given amount of radiation, one about 50 and one about 100 hours after the larvae hatch from the egg. The entire larval period from 40 to 100 hours after hatching is one of fairly high phenocopy production, higher than the first 24 hours of pupal life. Some pupae showed very high percentages of phenocopies, up to 400 per cent (400 phenocopies per 100 flies), but this was caused by the fact that the pupae can withstand more energy for the production of phenocopies without being killed. The high percentages of pheno- copies were the result of irradiations with 13,200 or 26,400 Since these dosages killed 100 per cent of the flies irradiated at most of the ages used, no lines were drawn for them on Figure 2. In 7- to 12-hour pupae, irradiations of 3,960 gave 120 phenocopies per 100 flies, 13,200 , 200 pheno- copies per 100 flies, and 26,400 , 300 phenocopies per 100 flies. The phenocopie
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
